70 results about "Circumferential strain" patented technology

The present invention relates to a method of measuring motion of an object such as a heart by magnetic resonance imaging. A pulse sequence is applied to spatially modulate a region of interest of the object and at least one first spectral peak is acquired from the Fourier domain of the spatially modulated object. The inverse Fourier transform information of the acquired first spectral-peaks is computed and a computed first harmonic phase image is determined from each spectral peak. The process is repeated to create a second harmonic phase image from each second spectral peak and the strain is determined from the first and second harmonic phase images. In a preferred embodiment, the method is employed to determine strain within the myocardium and to determine change in position of a point at two different times which may result in an increased distance or reduced distance. The method may be employed to determine the path of motion of a point through a sequence of tag images depicting movement of the heart. The method may be employed to determine circumferential strain and radial strain.

The invention relates to a method for monitoring the stress of a casing in a well by applying optical-fiber sensors, which mainly solves the problem that the existing research field of the casing erosion of an oil field and oil-water well does not have a direct method for monitoring the stress loading process of the casing in the well and the morphological characters of the casing erosion. The method is characterized in that: optical-fiber grating sensors are circumferentially arranged along the outer surface of the casing; a ground optical-fiber grating demodulation instrument connected with the optical-fiber grating sensors is utilized to monitor the circumferential strain Epsilon Theta of the casing and obtain the circumferential strain data of the casing; meanwhile, Brilliouin optical-fiber sensors are axially arranged along the outer surface of the casing; a ground Brilliouin optical-fiber demodulation instrument connected with the Brilliouin optical-fiber sensors is utilized to monitor the axial strain Epsilon Z of the casing and obtain the axial stain data of the casing; and the obtained circumferential strain Epsilon Theta and the axial strain Epsilon Z of the casing are utilized to obtain the stress of the outer layer of the casing in the well according to a ground stress explanation model. The method is characterized by being capable of permanently monitoring the deformation of the casing and obtaining corresponding stratum pressure under the condition without knowing the casing erosion and the stratum pressure.

An apparatus for varying the gain of a fiber optic sensor that non-intrusively senses the strain response of a pipe is provided. The apparatus includes a circumferential strain attenuator that has an annular land portion that mechanically couples the attenuator to the pipe. An annular web extends coaxially from the land portion and has a reduced cross sectional area relative to the land, and an annular mandrel portion extends coaxially from the web portion and forms a gap between the pipe and the mandrel. The fiber optic sensor is wound on the circumferential strain attenuator. The web and mandrel cooperate to reduce the strain response of the fiber optic sensor relative to the strain response of the pipe.

The invention relates to a method for monitoring the circumferential strain of a casing by applying optical-fiber grating sensors, which mainly solves the problem that an electric-resistance strain gauge adopted of the current technology for monitoring the circumferential deformation of the casing is easy to be affected by electromagnetism in a well and corrosion, thus causing a measured circumferential strain signal of the casing to be inaccurate. The method is characterized in that: the optical-fiber grating sensors are arranged outside the casing along the circumferential direction of the casing, wherein, a plurality of optical-fiber grating sensors are evenly arranged around the casing; sections of adjacent intervals form a certain angle; an optical-fiber temperature compensating sensor is arranged in a position at a corresponding distance away from the group of sensors; the optical-fiber grating sensors are applied to monitoring the circumferential deformation and stress status of the casing within certain ranges; meanwhile, the temperature compensating sensor is applied to serving the temperature compensation and temperature monitoring in the well of the strain sensor; the sensors transmit underground signals to the ground by a transmission optical cable; and the signals can be transformed into the circumferential strain information of the casing after a demodulation instrument obtains the signals and carries out secondary treatment. The method is characterized by not being affected by the underground electromagnetism.

A system for hemodynamic simulation comprises a vessel having properties of a blood vessel, a reservoir containing a quantity of fluid, tubing connecting the vessel and reservoir, and at least one pump for circulating the fluid within the system. Fluid can be tissue culture medium or blood analog fluid, and the vessel may include mammalian cells attached to its inside. A drive system, comprising two reciprocating drive shafts that are coupled by a cam, enables the uncoupling of pulsatile flow and pulsatile pressure to provide independent control over wall shear stress and circumferential strain. The shaft drives two pumps that are 180 degrees out-of-phase and are connected upstream and downstream of the vessel, and effect this uncoupling.

The invention discloses a method for measuring and calculating circumferential strain of a rock sample by utilizing a distributed-type optical fiber grating sensing network. The method includes: arranging two sets of optical fiber grating sensors which are in series connection on a rubber sleeve coated on the outer surface of the rock sample at an interval along the peripheral direction and the axial direction of the rock sample in a staggered mesh form to form the optical fiber grating sensing network to measure and calculate local strain of each point in the circumferential direction of the rock sample; enabling each optical fiber grating sensor to be serially connected with one temperature compensation sensor to finally acquire circumferential strain of the rock sample and a circumferential deformation diagram of the rock sample at each transient time. Distributed mesh type sensor layout is utilized, so that accurate local strain monitoring of the circumferential surface of the rock sample can be realized while circumferential deformation diagram of the rock sample at a certain transient moment is acquired, knowing of deformation features of the rock sample at each stage of an experiment is facilitated, and circumferential strain features of the rock sample can be reflected more objectively.

The invention discloses a method for determining effective stress coefficients of a rock. The method comprises the steps of preparing a rock test sample and measuring and recording the size of the rock sample; loading the rock sample into a pressure chamber of a triaxial servometer, loading confining pressure to a predetermined value, keeping the confining pressure, constantly loading bias, loading the bias to a set value, unloading, keeping the bias and the confining pressure constant and loading pore water pressure; repeating the previous step and loading the bias until the rock sample is destroyed; drawing a relation curve of bias increments and axial/circumferential strain increment under different confining pressure and carrying out data fitting on the curve to obtain an effective elastic modulus E1 and poisson ratio v31 related to bias grades; and calculating an axial effective stress coefficient and a circumferential effective stress coefficient of the rock sample through a formula. The effective stress coefficients obtained through the method are accurate and reliable, and can be applied to numerical calculation of seepage and stress coupling in practical engineering, the calculation accuracy is greatly improved and the analysis error is reduced.

The invention relates to an axial pre-tightening force sensor. The axial pre-tightening force sensor comprises a regulating gasket 2, a left end cover 3, an elastic sensitive element 4, a strain gage 5, a right end cover 6, a thrust ball bearing 7, an axial hole groove 9, a right bolt 10, a fairlead 11, a package shell 12 and a left bolt 13. The regulating gasket is used for regulating the axial position of the sensor on a shaft, the left end cover and the right end cover support the elastic sensitive element through bosses, the elastic sensitive element generates axial strain because of bearing axial force, and the axial force can be measured through the resistance strain effect and a measuring circuit. The axial hole groove 9 in the right end cover 6 of the sensor is matched with the right bolt 10 to be used for preventing the elastic sensitive element from generating circumferential strain in a pre-tightening process, axial displacement of the right end cover 6 and axial strain of the elastic sensitive element 4 are allowed, and the thrust ball bearing is used for insulating circumferential twisting force generated when the pre-tightening force is exerted so that the axial twisting force can be prevented from being transmitted to the elastic sensitive element 4.

The invention discloses a multiple-factor accelerated aging test device for a composite material electric pole. The multiple-factor accelerated aging test device comprises an aging test room, wherein water nozzles and acid, alkali and salt atomizers are arranged on the roof surface of the aging test room; ozone generators, ultraviolet lamps, high-temperature and low-temperature humidity-heat devices, and a tensile machine are arranged on the side walls of the aging test room respectively; the action end of the tensile machine is connected with a traction rod which is provided with a force meter; corresponding to the composite material electric pole to be tested, weights, leads, longitudinal strain gratings, circumferential strain gratings, and a signal detection processor which is electrically connected with the force meter, the longitudinal strain gratings and the circumferential strain gratings respectively, are arranged inside the aging test room. By the cooperation of the water nozzles, the acid, alkali and salt atomizers, the ozone generators, the ultraviolet lamps, the high-temperature and low-temperature humidity-heat devices, the tensile machine, the weights and the leads, various natural environments can be simulated comprehensively, so that the performance of the composite material electric pole can be thoughtfully and correctly tested. The accelerated aging test device is applicable to testing of pole towers.

The invention discloses an online identification method for multiple loads on blades of a large wind power generation set. The method includes following steps that 1, the transformation relation between coordinate systems of the large wind power generation set is set; 2, the arrangement mode of blade root circumferential strain gages and blade axial strain gages is determined; 3, a data processing algorithm is adopted for decomposing the multiple loads on the blades; 4, an outline deformation correction algorithm is adopted for correcting the loads. By means of the method, the multiple loads such as gravitational loads, centrifugal force loads, inertial loads and complex aerodynamic loads can be effectively extracted and identified on line, the information of gravity, centrifugal force, inertia force, aerodynamic force and the like can be extracted from measured data, a computer is adopted for performing real-time computing on the computing algorithms, rapid and accurate online identification of the multiple loads on the large blades is performed, and it is guaranteed that the large wind power generation set operates safely and reliably in the service cycle.

A system for hemodynamic simulation comprises a vessel having properties of a blood vessel, a reservoir containing a quantity of fluid, tubing connecting the vessel and reservoir, and at least one pump for circulating the fluid within the system. Fluid can be tissue culture medium or blood analog fluid, and the vessel may include mammalian cells attached to its inside. A drive system, comprising two reciprocating drive shafts that are coupled by a cam, enables the uncoupling of pulsatile flow and pulsatile pressure to provide independent control over wall shear stress and circumferential strain. The shaft drives two pumps that are 180 degrees out-of-phase and are connected upstream and downstream of the vessel, and effect this uncoupling.

The invention discloses a circumferential intelligentized reinforcement structure and method of a shield tunnel. A reinforcing and monitoring integrated structure is formed through intelligent fiber composite ribs with built-in distributed optical fiber sensors, circumferentially arranged along the inner side surface of the tunnel. The method comprises the following steps: bonding intelligent FRP (fiber reinforced plastic) ribs with the inner side of the tunnel through bonding materials to form a structure layer with good mechanical property; calculating the circumferential convergence of the structure by monitored circumferential strain, and judging the performance change of the reinforced structure. According to the circumferential intelligentized reinforcement structure and method, facilities are simple, the engineering construction is convenient, the difficult problem of reinforcing and monitoring integration of the conventional shield tunnel can be solved, the market competitiveness is high, and large-scale popularization is facilitated.

A stretch flange crack prediction method of predicting initiation of stretch flange cracks that occurs in a flange end section during stretch flange forming of a deformable sheet, includes: a measurement value acquisition process of acquiring, for each of a plurality of sheet-shaped test pieces, a fracture strain measurement value, a normal strain gradient measurement value, and a circumferential strain gradient measurement value; a CAE analysis process of acquiring a maximum major strain maximum element having a highest maximum major strain, a normal strain gradient of the maximum major strain maximum element, and a circumferential strain gradient of the maximum major strain maximum element; a fracture determination threshold acquisition process of acquiring a fracture determination threshold by converting the fracture strain measurement value; and a prediction process of predicting that stretch flange cracks will be initiated, when the maximum major strain is equal to or higher than the fracture determination threshold.

The invention relates to an intelligent anchorage device, which comprises anchor rings and a split type anchorage device body used for clamping an anchor rod steel strand, wherein the anchor rings comprise a first anchor ring and a second anchor ring, the first anchor ring and the second anchor ring are locked together through a connecting piece, an anchorage device mounting groove used for mounting the split type anchorage device body is defined by the first anchor ring and the second anchor ring, the intelligent anchorage device further comprises a strain gauges used for sensing the circumferential strains of the anchor rings, compensation gauges used for compensating strain difference caused by temperature, and a data collector, and the strain gauges are connected to the data collectorthrough conducting wires, and are fixed to the outer walls of the anchor rings in the circumferential directions of the anchor rings. The invention further provides a method for testing the axial force of an anchor rod by adopting the intelligent anchorage device. The intelligent anchorage device has the advantages of being simple in structure, convenient to operate and high in measurement precision.

Disclosed in the invention is a circumferential strain gauge for an inner wall of a circular hole. The circumferential strain gauge comprises a rigid ring; and an opening is formed in the rigid ring. A first support and a second support that are arranged in parallel are arranged in the rigid ring; and one end of each of the first support and the second support is fixed at the opening. In addition, the circumferential strain gauge also includes a first steel plate and a strain sensor; the strain sensor consists of a second steel plate and a resistor plate; a groove is formed in the second steel plate and the resistor plate is attached to the bottom of the groove; and a cable connected with the resistor plate is led out from a circular hole. One end of the first steel plate is fixedly connected with the other end of the first support; and the other end of the first steel plate is provided with a screw penetrating the first steel plate. The end of the screw is abutted against one end of the second steel plate; and the other end of the second steel plate is fixed at the other end of the second support. The first steel plate and the second steel plate are arranged horizontally. The provided circumferential strain gauge has advantages of reasonable design, simple structure, and high sensitivity and stability and is suitable for strain measurement of an inner hole.

The invention discloses a rock-soil material penetration deformation testing method under complex stress state and test device. The test method comprises those steps as follows: fabricate the cylindrical sample, measure and record the sample size; consequently, the sample is placed inside the pressure chamber which is fully closed, and the confining pressure is loaded up to the target value and kept the same controlled by servo. Afterwards, the servo controls the multi-stage osmotic loading pressure and record the water flow volume, axial deformation and circumferential deformation of sample when the osmosis passes through the sample with times so as to determine the changes on osmotic coefficient, axial strain and the circumferential strain of sample, which reflects the osmosis deformation status of sample. It is repeated that the confining pressure and osmosis pressure are loaded which is controlled by servo to achieve the osmosis deformation status of rock-soil material under complex stress state. The test device comprises pressure chamber, confining pressure servo loading system and osmotic pressure servo loading system. The sample is fixed inside the pressure chamber and arranged with an axial strain gauge. The upper part, the middle part and the lower part of the sample are respectively provided with a circumferential strain gauge.

The present invention relates to a method for measuring the liquid-metal surface level (13) and the slag surface level (14) in the crucible (1) of a metallurgical shaft furnace comprising the following steps: measuring, at one or more points on the external wall (2) of the crucible, the following variables: the circumferential strain in said external wall (2) by means of a number of strain-gauge sensors (6) fixed to the armour (4) of the external wall (2) of the crucible; and the temperature of said external wall (2) by means of one or more temperature sensors (7) fixed to the armour (4) of the external wall (2) of the crucible; introducing said variables measured at a number of points on the external wall of the crucible into the general equation governing circumferential strain, the solution of which is analytical, and which contains two unknowns, the liquid metal level and the overall liquid metal/slag level, considering set parameters; and solving said equation and obtaining an analytical solution giving the liquid metal surface level (13) and the slag surface level (14) in the crucible (1).

The invention discloses a method for obtaining a shrinkage strain ratio in continuous change of a titanium alloy tube. A tube test sample is machined according to the size of a metal tube test sample in GB/T228-2002. A tensile test is carried out on a tensile test machine in a set tensile speed. The changes of the circumferential strain and the axial strain of the tube test sample in the tensile process are both precisely obtained through a CCD (Charge Coupled Device) camera. The circumferential strain and axial strain values of the tube test sample are precisely measured by using the camera in the one-way tensile process, and are subjected to elastic corrosion so as to accurately obtain the shrinkage stain ratio of the titanium alloy tube under a large plasticity deformation condition in the tensile process through formulas; and moreover the shrinkage strain ratio of the titanium alloy tube is decreased, that is, in the primary deformation period of the tube test sample, the shrinkage stain ratio is decreased dramatically, however, in later deformation, the decrease tendency of the shrinkage stain ratio is gradually reduced, and the decrease tendency of the shrinkage stain ratio in later deformation is gradually stable.

The invention discloses a method for quickly evaluating the leakage rate of a multilayer pressure-bearing shell based on a flow conservation theorem, and belongs to the field of evaluation of the leakage rate of a damaged pressure-bearing structure. The main principle of the method is as follows: based on an ideal elastic-plastic constitutive, considering the cracking process and the failure mechanism of the multilayer pressure-bearing shell, quickly estimating the circumferential strain distribution of each layer of shell, and estimating the circumferential crack opening on the basis of exceeding the tensile limit strain of the material; and based on the flow conservation theorem, calculating the overall leakage rate of the shell structure with inconsistent cracking degree of each layer.According to the method, the cracking condition of the multi-layer pressure-bearing shell under the action of the internal pressure of a serious accident can be estimated, and the gas leakage rate ofthe multi-layer shell walls with different cracking degrees can be quickly estimated.

A method for calculating deformation and stress of tunnel under non-uniform explosion load comprises the following steps: it is assumed that non-uniform explosion load exist in an infinite medium-hard rock tunnel, the tunnel model is simplified as a rock mass-plane strain model of single-layer lining; according to the elastic wave theory, the governing equation of rock mass is established, and the constitutive equation and constitutive relation of rock mass are deduced to make the transient load, circumferential strain and shear strain change with a formula(shown in the specification). The potential function is introduced to decouple the equilibrium equation of rock mass. The modal equation of a shell in polar coordinates is established, and the relationship between stress and displacement of lining is obtained. The boundary conditions are introduced to solve the undetermined coefficients, and the Internal force solution in tunnel-rock mass is obtained.

The invention provides a method and system for calculating extrusion stress of an isotropic double-pipe concrete column, and the method comprises the steps: 1, obtaining calculation parameters of a double-pipe concrete column, including the Poisson's ratio and elastic modulus of internal core concrete and external interlayer concrete, and the Poisson's ratio, elastic modulus, inner diameter and wall thickness of an internal pipe and an external pipe; 2, establishing an extrusion stress relationship among all parts of the double-pipe concrete column; 3, substituting calculation parameters into the step 2 to obtain the extrusion stress between the parts; 4, based on the calculation parameters and the result obtained through solving in the step 3, obtaining the annular and radial strain of the inner core concrete, the annular stress and the annular strain of the inner pipe, the radial and annular stress of the outer interlayer concrete changing along the thickness and the radial and annular strain of the outer interlayer concrete changing along the thickness, the circumferential strain of the inner side and the outer side of the outer interlayer concrete and the circumferential stress and the circumferential strain of the outer pipe.

The invention provides a method for measuring the multi-axis strain of a thin-walled tube under an internal pressure axial composite load. The method comprises the steps that a standard test mark is made on the surface of the thin-walled tube as the reference of image processing; a CCD camera is used to display the image of the standard test mark on the measured thin-walled tube in the process of an axial fatigue and internal pressure composite test in real time; the distance between the axis direction and the circumferential direction of the mark are determined; the distance between two adjacent furthest edges between two axial strain marks and the change of the distance between two adjacent furthest edges between two circumferential strain marks are used to calculate strain measurement values; variable values are output to a host computer, and are displayed and stored; the digital signal of axial and circumferential strain measurement values is converted into an analog signal, and the signal is output; and a common interface is provided for a general mechanical test device. The method provided by the invention has the advantages of flexible test range adjustment and good dynamic response characteristic, is suitable for real-time acquisition of axial and circumferential strain of various metal and non-metallic thin-walled tubes, and can be used for high temperature low-cycle and high-cycle fatigue tests of metal materials and non-metallic materials.